1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copying machine or a printer, including a control unit for saving energy, a method of controlling the image forming apparatus, and a storage medium.
2. Description of the Related Art
In general, the price of an image forming apparatus, such as a copying machine or a printer, has been progressively reduced, and therefore demand for price reduction of a control unit for controlling a printer has been increasing.
Further, printers configured to print out an image based on print data received from a host computer include a host-based type that employs, with a view to cost reduction, a printing method in which a host computer rasterizes print data into a format which can be output by the printer, and then delivers the rasterized data to the printer.
As such printers described above, with a tendency toward reduction of apparatus size and price, there has appeared a type which is configured to dispense with a cooling unit, such as a fan. Further, some printers of this type are provided with a temperature rise control mode in which a predetermined cooling time is provided when the printer internal temperature has risen, thereby disabling a printing operation until the printer internal temperature falls.
Further, there has conventionally been proposed a printer that achieves energy saving by preventing wasteful heater energization (see Japanese Patent Laid-Open Publication No. 2006-227395). In this printer, it is determined whether or not a printing device is in an energy saving state, or whether or not the temperature of a fixing unit is a temperature ready for printing when data is received by a data reception unit. If the printer is not in the energy saving state, or if the temperature is a temperature ready for printing, printing is performed, whereas if the printer is in the energy saving state, or if the temperature is not a temperature ready for printing, the received data is accumulated in an accumulation unit, and the printing is not performed. This prevents wasteful heater energization to thereby achieve energy saving.
In the field of small-sized printers, development of a printer without a cooling unit, such as a fan, has been proceeding so as to achieve reduction of apparatus size and costs.
In such a printer having no cooling unit, however, when continuous printing is performed, the printer internal temperature rises in a short time, and hence the printer shifts to the temperature rise control mode.
In such a small-sized printer provided with the temperature rise control mode and loaded with a small-sized cartridge, such an operation process is followed as illustrated, by way of example, in a timing diagram in FIG. 5 which shows printing time in continuous printing. In the operation process illustrated in FIG. 5, when continuous printing is started by a printer, the printer internal temperature rises and the printer shifts to the temperature rise control mode after printing of several tens of sheets. As a consequence, the printing operation is suspended until the printer internal temperature falls.
At this time, the printer is on standby while maintaining a state in which the printing operation can be resumed when the internal temperature falls by suspending the printing operation. Therefore, in the printer, during the temperature rise control mode, electric power is also supplied to functions which are not necessary when on standby, which causes wasteful electric power consumption.
Particularly, when continuous printing continues, the printing operation is performed while alternately repeating printing and the temperature rise control mode, which causes wasteful electric power consumption. Further to this, there is a problem that when continuous printing continues, the temperatures of a power supply unit and other units rise, which causes a delay in cooling the internal temperature of the apparatus.